wedge-shaped and may have air bronchograms. Nodules and masses may have central low attenuation and may cavitate. CT halo sign and reversed halo sign are also seen (Fig. 8.3). Reversed halo sign is an early sign seen in 4 % of patients with pulmonary fungal infection and is signiÞcantly more common in pulmonary mucormycosis than in invasive pulmonary aspergillosis [17].

CT–Pathology Comparisons

Reversed halo sign in invasive fungal infection are histopathologically associated with infarcted lung tissue, with a greater amount of hemorrhage at the periphery than in the center [17].

Patient Prognosis

Timely diagnosis of pulmonary mucormycosis is critical in the outcome of this infection because it rapidly spreads to the contralateral lung and distal organs if not promptly treated. The Þrst-line antifungal agents typically used for aspergillosis, such as voriconazole, lack activity against Mucorales. The overall mortality rate of pulmonary mucormycosis ranges from 50 to 70 % but increases up to 95 % with extrathoracic dissemination. To improve survival, surgical debridement of infected tissue as well as antifungal agents should be performed on an urgent basis.

the other organ involvements of the skin, central nervous system, and kidney can occur.

CT Findings

Characteristic CT Þndings are pulmonary nodules and masses with central low attenuation and peripheral rim enhancement, ground-glass halo, or reversed halo sign [6, 20] (Fig. 8.4). The nodules and masses are lower lobe predominant with a peribronchovascular and/or subpleural distribution [20]. Coarse irregular opacities and small thin-walled cysts are also seen [21].

CT–Pathology Comparisons

Pulmonary nodules and masses are histologically caused by intravascular and perivascular inÞltration of atypical lymphoid cells [21]. A low-attenuation center is corresponded to the histologic Þndings of central necrosis, and peripheral rim enhancement of the nodules is related to the angioinvasive and angio-destructive nature of lymphomatoid granulomatosis [20].

Reversed halo sign in lymphomatoid granulomatosis may be related to a central area of airspace Þlling with edema ßuid and foamy histiocytes, surrounded by a denser rim of lymphocytic inÞltration [6].

Lymphomatoid Granulomatosis

Pathology and Pathogenesis

The lungs contain nodules of pinkish-gray tissue, the largest of which show central necrosis and cavitation. Alternatively, areasofconßuentconsolidationmaybeseen.Microscopically, most cases show broad tracts of necrosis separated by a mixed angiocentric inÞltrate that includes usually scanty pleomorphic atypical lymphoid cells. While most of the lymphocytes stain for T-cell markers, the atypical lymphoid cells stain as B cells. The degree of cellular atypia varies considerably. The lesions are graded 1Ð3 on the degree of lymphocytic atypia, the presence of necrosis, and the polymorphic/ monomorphic nature of the inÞltrate, grade 3 lesions being synonymous with angiocentric lymphomas [18].

Symptoms and Signs

The most common symptoms include fever, persistent productive cough, dyspnea, and chest tightness [19]. The presentation is typically insidious, and lung lesions may wax and wane. Constitutional symptoms such as weight loss, malaise, and fatigue may be present. Symptoms related to

Patient Prognosis

Lymphomatoid granulomatosis is usually an EBV-driven lymphoproliferative disease in immunocompromised patients; immunosuppressive agents should be discontinued if at all. SpeciÞc therapy with corticosteroids, anti-CD20 monoclonal antibodies such as rituximab, interferon-alpha- 2b, and combination chemotherapy have showed a variable success rate [19].

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